Optimization of skeletal muscle for actuator of assisted circulation

骨骼肌预处理后输出功率的降低是骨骼肌应用于辅助循环的重要问题之一。为了解决这一问题，我们构建了由兔背阔肌（LDM）组成的骨骼肌心室（SMV），为建立新的训练方法提供了新的途径。以2 Hz连续刺激法对家兔左侧LDM进行10周的原位电预处理，并将其定义为训练组，而将右侧LDM定义为对照组。我们使用两种LDM构建了SMV，并使用模拟循环评估了SMV的基本性能。经过训练的LDM每搏作功（SW）较小，80 mmHg后负荷时最大SW相当于兔左心（LH）SW的67%，30 mmHg后负荷时最大SW相当于兔右心（RH）SW的184%。接下来的研究是进行开发泵系统的线性配置与驱动器的LDM。基于肌肉特性，对线性骨骼肌泵系统的功率进行了估计，并研究了线性骨骼肌泵系统的失效性。为了评估功效，成年山羊的原位LDM接受12周的预处理，然后进行功效分析。从预处理的LDM获得了良好的抗疲劳性和120分钟时的最高最大外部功率3.16W/kg。假设人体双侧LDM的重量为0.5kg，估计功率为1.58W。如果将该系统应用于LH辅助，则该系统的效率应大于50%。要实现线性肌肉泵系统，必须努力降低功率损耗。

Reduction of the putput power of skeletal muscle after preconditioning is one of the important problems in application of skeletal muscle for assited circulation. To solve this problem we constructed skeletal muscle ventricle (SMV) composed of rabbit latissimus dorsi muscle (LDM) with which new training methods can be established. Left LDMs of rabbit were electrically preconditioned in situ by 2 Hz continuous stimulation for 10 weeks and defined as trained, while right LDMs were defined as control. We constructed SMV uisng both LDMs and evaluated the basic performance of SMV with mock circulation. Stroke work (SW) was smaller in trained LDM and maximum SW at afterload of 80 mmHg was equal to 67% of rabbit left heart (LH) SW and maximum SW at afterload of 30 mmHg was equal to 184% of rabbit right heart (RH) SW.In endurance test, only trained LDM could work over 4 min and maintained 66% of rabbit RH SW at 1 hour. Next study was conducted to develop the pump system with anactuator of the LDM in linear configuration. The power of the LDM was estimated and the deasibility of a linear-skeletal muscle pump system was investigated based on the muscular property. To evaluate the power, in-situ LDMs in adult goats received 12-week preconditioning, followed by power analysis. Good fatigue resistance and the highest maximum external power of 3.16 Watts/kg at 120 minutes was derived from preconditioned LDM.Assuming that the weight of human bilateral LDMs is 0.5kg, estimated power became 1.58 Watts. If the system is applied to LH assistance, the efficiency of the system should be more than 50 %. To realize the linear-skeletl muscle pump system, much effort should be make to decrease the power loss.